Police have seized thousands of cannabis plants in a raid on property in Queensland's Southern Downs this morning.

Officers from the State Crime Operations Command discovered between 2000 and 3000 mature specimens and two sheds containing as many as 14,000 drying cannabis plants at  Kinvarra, a rural property on Hollybank Road at Warroo, west of Stanthorpe.   The sheds covered an area of about 1800 square metres - or twice the size of a suburban house block - police said.

A loaded semi-automatic pistol, ammunition and 60 200-litre drums of harvested cannabis were also found.

Regional crime co-ordinator Detective Inspector Noel Ragh said a tip from the public had led to the massive marijuana haul and had prevented the drugs from hitting Queensland's streets.

"The public is the eyes and ears of the Queensland Police Service, without their support our job would be that much harder,'' Detective Inspector Ragh said.

"Today's seizure is the culmination of months of intelligence and investigation. The result speaks for itself."

A 54-year-old man and his 28-year-old son have been charged with producing and possessing a dangerous drug, unlawful possession of a handgun, possessing property suspected of being the proceeds of a crime and possessing property suspected to have been used in connection with the commission of a drug offence.

Acting Detective Inspector Kerry Johnson, of the State Drug Squad, said the cannabis would eventually go up in smoke - but not as originally intended.

"The plants and harvested cannabis will be examined by a botanist before being destroyed," Detective Inspector Johnson said.

Both men will front the Warwick Magistrates Court later today.